https://github.com/d-sonuga/reverse-linear-scan-regalloc-concept

A toy register allocator to try out the reverse linear scan register allocator algorithm
https://github.com/d-sonuga/reverse-linear-scan-regalloc-concept

Last synced: 12 days ago
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A toy register allocator to try out the reverse linear scan register allocator algorithm

• Host: GitHub
• URL: https://github.com/d-sonuga/reverse-linear-scan-regalloc-concept
• Owner: d-sonuga
• Created: 2024-03-04T18:33:22.000Z (12 months ago)
• Default Branch: main
• Last Pushed: 2024-03-05T16:21:26.000Z (11 months ago)
• Last Synced: 2024-03-17T16:36:28.192Z (11 months ago)
• Language: Rust
• Size: 16.6 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Reverse Linear Scan Allocator Concept

A toy register allocator to implement the algorithm described in https://www.mattkeeter.com/blog/2022-10-04-ssra/.

Accepts a program with only `add`, `sub`, `save`, `load` and `store` commands. `store` can only store a 

constant in a virtual register. `add` and `sub` can only operate on registers. `save` copies a value from a

register to a stack slot and `load` copies a value from a stack slot to a register.

The input is expected not to have any `save` or `load` instructions.

The first operand is the output register. The rest are the input registers.

Registers are assumed to be of the form `vn` where `n` is the register number.

SSA form is assumed.

For example, a sample program with 5 virtual registers:

```

store v0 5

store v1 6

add v2 v0 v1

add v3 v2 v1

sub v4 v0 v3

```

A sample output with only 2 physical registers.:

```

store r0 5

store r1 6

save stack+0 r0

add r0 r0 r1

add r0 r0 r1

load r1 stack+0

sub r1 r1 r0

```

To run the sample input with 2 physical registers:

```

cargo run sample/input 2

```